java programmer certification

garbage value of each region, that is, the amount of space and time it takes to reclaim the region, and then maintains a priority queue, recovering one of the most valuable region per time, based on the allowable collection times.To avoid the garbage collection problems caused by the cross-referencing of each region, each region of G1 has a remembered Set that stores references to other region's objects in this region. When a memory is reclaimed, this part is also added when enumerating GC root

returnYELLOW; }}, RED (30) {@Override PublicTrafficlamp Nextlamp () {//TODO auto-generated Method Stub returnGREEN; }}, YELLOW (5) {@Override PublicTrafficlamp Nextlamp () {//TODO auto-generated Method Stub returnRED; } }; Private intTime ; PrivateTrafficlamp (intTime) { This. time=Time ;} Public AbstractTrafficlamp Nextlamp (); }　Enumeration Class Summary:　　　1, the enumeration class is a special form of

for monitoring processing Closeitem.addactionlistener (NewActionListener () { Public voidactionperformed (ActionEvent e) {system.exit (0); } });　　　　//The form itself listens for processing F.addwindowlistener (NewWindowadapter () { Public voidwindowclosing (windowevent e) {system.exit (0); } }); } Public Static voidMain (string[] args) {Newmymenutest (); }}Summarize:Event Monitoring mechanism:　1. Determine the event source (container or component)2. The listener is regi

inserted into the database can not be deleted!9. Distribution filteringWhen we enter the (F5) method, we can also access its external libraries (such as java.*), we may not need this library, we can add a filter on the Perference tab page to exclude this package.10. Entering, jumping and returningI put this on the last point, during the commissioning process, these are things that must be understood (preferably mastered):f5--Enter: Moves to the next

If you're a Java programmer with a passion for technology, here are 10 key points to stand out among the many Java developers.1. Have a solid foundation and a deep understanding of OO principlesFor Java programmers, a deep understanding of the concept of Object oriented programming (OO programming) is a must. Without a

Original: http://www.fromdev.com/2012/01/25-best-free-eclipse-plug-ins-for-java.html"工欲善其事, must be the first weapon." Here are 25 commonly used eclipse plug-ins to improve Java programmer development efficiency. There are two similar "my favorite Eclipse plugin recommendations" on StackOverflow, and I think this article is almost based on this recommendation: http://stackoverflow.com/questions/2826/ Do-you

the ape friends, generally will be more impatient gas manic, the technical curiosity is strong, especially some tall technology, what big data, cloud computing, architecture, and so on, some biased to technical research, some biased in business. Most programmers may choose to be biased in favor of technical research, so they are less likely to be interested in business, and therefore feel that doing it every day is no fun. At this time, calm down to analyze what kind of direction you are. Can y

Program | Programmer java programmer must read: Basic time: 2001/09/13 13:31 Author: ZSC Pacific Network College 　 2.2 What is the message The interaction between software objects and communication is the use of messages. A single object is usually not very useful. Instead, an object is usually a larger program or application that contains many other obje

Dark Horse programmer-java basic IO stream-bytes stream buffer and word throttling, javaio Shard Stream Buffer L the emergence of a buffer increases the efficiency of reading and writing data. L corresponding class • BufferedWriter • BufferedReader L the buffer zone can be used only when combined with the stream. L The streaming function is enhanced based on the stream. 1, BufferedWriter Each time a row c

first converted to high-precision re-operation. Long L_1 = 123;// Automatic data type conversion3. forced type conversion: high-precision to low-precision non-forced type conversion will be error, but high precision to low precision conversion will lose precision, it is recommended not to do so. float f_1 = (float) d_1;4. Data accuracy from low to High:byte5. If the integer does not exceed the range of byte, short ,char, You can assign this integer directly to byte, short,char 6. A variety of d

) = 1;Analysis: x1=1; X2=1; x3=x1+x2; x4=x2+x3; ... ; Xn=x (n-1) +x (n-2)public int F (int n) {if (n==1) {return 1;}else if (n==2) {return 1;}else{Return F (n-1) +f (n-2);}}4.java reverse printing of individual elements in an integer array using a recursive methodpublic static void printall (int index,int[] arr) {System.out.println (Arr[index]);if (Index > 0) {Printall (--index,arr);}}public static void Main (string[] args) {Int[] arr={1,2,3,4,5};Prin

|0086): This can be +86 or 0086.2. String is a regular correlation API2.1. Matches methodThe parameters of the matches () method require that we pass in a regular expression that is described by a string, and then use the string formatting rules described by the regular expression to match the current string, if satisfied then the method returns True. Otherwise, false is returned.For example:String emailRegEx ="^[a-zA-Z0-9_.-][emailprotected]([a-zA-Z0-9-]+\\.)+[a-zA-Z0-9]{2,4}$";String email ="[

{// Code to ensure thread safety }15 finally16 { lock.unlock (); }19 }20}When using the lock object to ensure synchronization, Java provides the Condition class to maintain coordination, that is, Condition replaces the functionality of the synchronization monitor.The Condition instance is essentially bound to a lock object. Such as:1// define lock object 2 private final reentra

) {this.colorname = n;} Public String Getcolorname () {return this.colorname;} abstract void Show ();3. Enumeration of common methods in a class, using an enumeration object to invokeint CompareTo (E o)//Compare the index value of the enumerated item, do subtractionString name ()//name of the enumeration entry fieldnameint ordinal ()//index value of the enumeration entryString toString ()//The corresponding fieldname of the enumeration objectVALUES ()Although this method is not found in the JDK

array: Initializing a two-dimensional array is similar to initializing the same-dimensional array, and you can also use curly braces to initialize the two-dimensional array. The syntax is as follows:Type arrayname[][] = {Value1,value2...valuen};Type: Array data typeArrayname: array name, a valid identifierValue: The values of the elements in the arrayExample: Create a class matrix in a project, write code in the main method to output a matrix of 3 rows and 4 columns and all elements are 0.publi

} - -}Output Result:I'm a statement block outputBefore the constructor is calledI'm the constructor.After the constructor is calledStatic import:If you access a static member of a class, you must qualify a reference to the class.Since Java SE5.0 ,theJava language provides a static import feature that allows users to have unqualified access to static members without the use of qualified class names. math 1 import Java.lang.Math; 3 cla

San";Age = 18;}Public Basicinfo (String name, intage) {Super ();THIS.name = name;This.age = age;}@OverridePublic String toString () {Return "Basicinfo[name=" + name + ", age=" + Age + "]";}}The student class inherits from the Basicinfo class, the constructor is also polymorphic, and the property school is encapsulatedpublic class Student extendsbasicinfo{Private String School;Public String Getschool () {return school;}public void Setschool (Stringschool) {This.school = School;}Public Student (S

, jumping and returningI put this on the last point, during the commissioning process, these are things that must be understood (preferably mastered):f5--Enter: Moves to the next step, if the current row has a method call, the control jumps to the first line of the called method execution.f6--jumps: Moves to the next line. If there is a method call on the current line, it is moved directly to the next line. Does not enter inside the called method body.f7--returns: Jumps out of the current method